Straightforward synthesis of novel cyclic metallasiloxanes supported by an N,C,N-chelating ligand

摘要

The reaction of an N,C,N-intramolecularly coordinated tin(iv) carbonate LSn(Ph)(CO_3) (1) and antimony(iii) and bismuth(iii) oxides (LMO)_2 (where M = Sb (2), Bi (3) and L = C_6H_3-2,6-(CH_2NMe_2)2) with (HO)SiPh_2(O)SiPh_2(OH) in 1:1 (in the case of 1) or 1:2 molar ratio (in the cases of 2 and 3) gave the metallasiloxanes cyclo-LSn(Ph)(OSiPh_2)2O (4) and cyclo-LM(OSiPh_2)2O (where M = Sb (6) and Bi (7)) containing six-membered MSi_2O_3 rings. Alternatively, the compounds 4, 6 and 7 can be also prepared reacting Ph_2Si(OH)_2 and compounds 1, 2 and 3, respectively, in the molar ratio of either 2:1 (for 4) or 4:1 (for 6 and 7). The reaction of Ph_2Si(OH)_2 with 1 in 1:1 molar ratio gave cyclo-Ph_2Si(OSnL(Ph)O)_2SiPh_2 (5) containing an eight-membered Sn_2Si_2O_4 stannasiloxane ring. The analogous eight-membered stibasiloxane derivative cyclo-Ph_2Si(OSbLO)_2SiPh_2 (8) was obtained as well, while attempts to synthesize the bismuth analogue failed. Compounds 1-3 react with the siloxane cyclo-(Me_2SiO)_3 providing either eight-membered metallasiloxanes cyclo-LSn(Ph)(OSiMe_2O)_2SiMe_2 (9) and cyclo-LSb(OSiMe_2O)_2SiMe_2 (10) or the six-membered bismutasiloxane cyclo-LBi(OSiMe_2)_2O (11). All compounds were characterized with the help of elemental analysis, ~1H, ~(13)C, ~(29)Si and ~(119)Sn NMR spectroscopy, and single crystal X-ray diffraction analyses (except 9 and 10).